specific defensive error handling

Implement specific exception handling and defensive programming practices to prevent generic errors from masking real issues and provide graceful degradation when operations fail.

Key principles:

1. Catch specific exceptions rather than generic Exception to avoid hiding legitimate errors
2. Implement defensive checks before accessing data structures or external resources
3. Provide sensible defaults when operations fail to ensure graceful degradation

Example of problematic generic exception handling:

try:
    ctnr.kill()
except Exception:  # Too broad - hides real issues
    pass

Better approach with specific exception handling:

try:
    ctnr.kill()
except docker.errors.APIError:  # Specific to expected failure
    log.warning(f"Failed to kill container {ctnr.name}")

Example of defensive programming:

# Check before accessing to prevent IndexError
containers = project.up(service_names=[service.name])
matching_containers = [c for c in containers if c.service == service.name]
if not matching_containers:
    raise OperationFailedError("Could not bring up the requested service")
container = matching_containers[0]

This approach ensures errors are handled appropriately without masking underlying issues, while providing users with meaningful feedback when operations fail.